triamterene and hydrochlorothiazide

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

GENERIC NAME: triamterene and hydrochlorothiazide (HCTZ)

BRAND NAMES: Maxzide, Dyazide

DRUG CLASS AND MECHANISM: Triamterene/hydrochlorothiazide is an oral diuretic
(water pill) that is used for treating
high blood pressure (hypertension) and
edema (water
accumulation). It is a combination of two different diuretics. The FDA approved
triamterene/hydrochlorothiazide in December 1965.

The kidneys control the amount of sodium and water within the body. Normally,
blood circulates through the kidneys where much of the water, sodium and other
small molecules are filtered out of the blood and into the tubules of the
kidney. Once in the tubules, much of the water and sodium are reabsorbed back
into the blood. The water and sodium that is not reabsorbed passes on through
the tubules and becomes urine that is eliminated from the body. Diuretics affect
the reabsorption of sodium and water from the tubules and thus, the amount of
sodium and water retained or eliminated by the body. In addition to controlling
sodium, the kidney also controls the amount of potassium that is retained or
eliminated from the body.

Diuretics eliminate salt (sodium) and water from the body.
Hydrochlorothiazide is a diuretic that can be used alone for treating high
blood pressure and edema. It works by blocking sodium and water reabsorption in
the kidneys, thereby reducing sodium and water in the body. (Whereas it is clear
how hydrochlorothiazide eliminates water from the body, its mechanism of action
in lowering high blood pressure is not well understood.) To compensate for the
increased amount of sodium and water in the tubules that will be lost as urine,
the kidney tries to reabsorb more sodium and water. It does this by removing
potassium from the blood and putting it into the tubules in exchange for sodium
(and water) in the tubules. As a result, blood potassium levels fall.
Triamterene is a diuretic that prevents reabsorption of sodium in exchange for
potassium. Thus, it reduces sodium and water in the body but also prevents the
depletion of potassium. For this reason, triamterene is called a potassium
sparing diuretic. By combining hydrochlorothiazide with triamterene, sodium and
water are eliminated from the body without the loss of potassium. However, this
drug may allow potassium levels to increase so potassium levels should be
closely monitored.